Sequential One-Pot Combination of Multireactions through Multicatalysis: A General Approach to Rapid Assembly of Functionalized Push−Pull Olefins, Phenols, and 2-Methyl-2H-chromenes

A metal- and catalyst-free photoinduced radical cascade hydroalkylation of 1,7-enynes has been disclosed. The process is triggered by a SET event involving a photoexcited electron-donor-aceptor complex between NHPI ester and Hantzsch ester, which decomposes to afford a tertiary radical that is readily trapped by the enyne. <a>The method provides an operationally simple, robust and step-economical approach to the construction of diversely functionalized dihydroquinolinones bearing quaternary-centers. A sequential one-pot hydroalkylation-isomerization approach is also allowed giving access to a family of quinolinones. A wide substrate scope and high functional group tolerance was observed in both approaches</a>.

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One-Pot Synthesis and Conformational Analysis of 6-Membered Cyclic Iodonium Salts

10.26434/chemrxiv.12234665 ◽

2020 ◽

Author(s):

Lucien Caspers ◽

Julian Spils ◽

Mattis Damrath ◽

Enno Lork ◽

Boris Nachtsheim

Keyword(s):

Conformational Analysis ◽

Bronsted Acids ◽

One Pot ◽

Benzyl Alcohols ◽

Iodonium Salts ◽

Efficient Approach ◽

One Pot Synthesis ◽

Diaryliodonium Salts

In this article we describe an efficient approach for the synthesis of cyclic diaryliodonium salts. The method is based on benzyl alcohols as starting materials and consists of an Friedel-Crafts-arylation/oxidation sequence. Besides a deep optimization, particluar focusing on the choice and ratios of the utilized Bronsted-acids and oxidants, we explore the substrate scope of this transformation. We also discuss an interesting isomerism of cyclic iodonium salts substituted with aliphatic substituents at the bridge head carbon.

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Metal-, and Organocatalyst-Free One-Pot Assembly of Chiral Aza-Tricyclic Molecules: Creating Six Contiguous Stereocenters from 2-D-Structures and an Amino Acid

10.26434/chemrxiv.12757943.v1 ◽

2020 ◽

Author(s):

Dung Do

Keyword(s):

Amino Acid ◽

Chemical Space ◽

Structural Diversity ◽

Therapeutic Agents ◽

Chiral Molecules ◽

One Pot ◽

Complex Molecules ◽

Chiral Catalyst ◽

Chiral Complex ◽

Free Process

Chiral molecules with their defined 3-D structures are of paramount importance for the study of chemical biology and drug discovery. Having rich structural diversity and unique stereoisomerism, chiral molecules offer a large chemical space that can be explored for the design of new therapeutic agents.1 Practically, chiral architectures are usually prepared from organometallic and organocatalytic processes where a transition metal or an organocatalyst is tailor-made for desired reactions. As a result, developing a method that enables rapid assembly of chiral complex molecules under metal- and organocatalyst-free condition represents a daunting challenge. Here we developed a straightforward route to create a chiral 3-D structure from 2-D structures and an amino acid without any chiral catalyst. The center of this research is the design of a <a>special chiral spiroimidazolidinone cyclohexadienone intermediate</a>, a merger of a chiral reactive substrate with multiple nucleophillic/electrophillic sites and a transient organocatalyst. <a>This unique substrate-catalyst (“subcatalyst”) dual role of the intermediate enhances </a><a>the coordinational proximity of the chiral substrate and catalyst</a> in the key Aza-Michael/Michael cascade resulting in a substantial steric discrimination and an excellent overall diastereoselectivity. Whereas the “subcatalyst” (hidden catalyst) is not present in the reaction’s initial components, which renders a chiral catalyst-free process, it is strategically produced to promote sequential self-catalyzed reactions. The success of this methodology will pave the way for many efficient preparations of chiral complex molecules and aid for the quest to create next generation of therapeutic agents.

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Room Temperature Alkali Metal Reduction of Carbon Dioxide

10.26434/chemrxiv.12665336 ◽

2020 ◽

Author(s):

Lucas A. Freeman ◽

Akachukwu D. Obi ◽

Haleigh R. Machost ◽

Andrew Molino ◽

Asa W. Nichols ◽

...

Keyword(s):

Alkali Metal ◽

Alkali Metals ◽

Room Temperature ◽

Chemical Reduction ◽

Bond Cleavage ◽

Open Shell ◽

Metal Reduction ◽

One Pot ◽

Earth Abundant ◽

Electron Reduction

The reduction of the relatively inert carbon–oxygen bonds of CO2 to access useful CO2-derived organic products is one of the most important fundamental challenges in synthetic chemistry. Facilitating this bond-cleavage using earth-abundant, non-toxic main group elements (MGEs) is especially arduous because of the difficulty in achieving strong inner-sphere interactions between CO2 and the MGE. Herein we report the first successful chemical reduction of CO2 at room temperature by alkali metals, promoted by a cyclic(alkyl)(amino) carbene (CAAC). One-electron reduction of CAAC-CO2 adduct (1) with lithium, sodium or potassium metal yields stable monoanionic radicals clusters [M(CAAC–CO2)]n(M = Li, Na, K, 2-4) and two-electron alkali metal reduction affords open-shell, dianionic clusters of the general formula [M2(CAAC–CO2)]n (5-8). It is notable that these crystalline clusters of reduced CO2 may also be isolated via the “one-pot” reaction of free CO2 with free CAAC followed by the addition of alkali metals – a reductive process which does not occur in the absence of carbene. Each of the products 2-8 were investigated using a combination of experimental and theoretical methods.

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A Series of Metal-Organic Frameworks for Selective CO2 Capture and Catalytic Oxidative Carboxylation of Olefins

10.26434/chemrxiv.7068509 ◽

2018 ◽

Author(s):

Huong T. D. Nguyen ◽

Y B. N. Tran ◽

Hung N. Nguyen ◽

Tranh C. Nguyen ◽

Felipe Gándara ◽

...

Keyword(s):

Room Temperature ◽

Gas Adsorption ◽

New Materials ◽

One Pot ◽

Acid Gas ◽

Naphthalene Diimide ◽

Styrene Carbonate ◽

Metal Organic ◽

Adsorption Of Co ◽

The One

Three novel lanthanide metal˗organic frameworks (Ln-MOFs), namely MOF-590, -591, and -592 were constructed from a naphthalene diimide tetracarboxylic acid. Gas adsorption measurements of MOF-591 and -592 revealed good adsorption of CO2 (low pressure, at room temperature) and moderate CO2 selectivity over N2 and CH4. Accordingly, breakthrough measurements were performed on a representative MOF-592, in which the separation of CO2 from binary mixture containing N2 and CO2 was demonstrated without any loss in performance over three consecutive cycles. Moreover, MOF-590, MOF-591, and MOF-592 exhibited catalytic activity in the one-pot synthesis of styrene carbonate from styrene and CO2 under mild conditions (1 atm CO2, 80 °C, and solvent-free). Among the new materials, MOF-590 revealed a remarkable efficiency with exceptional conversion (96%), selectivity (95%), and yield (91%).

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